You
may have seen conflicting reports about breast cancer screening over
the past few months. Even among doctors, opinions vary about what the
benefits of screening with breast mammography (x-rays) are and which
women should be screened. Experts at The University of Texas MD
Anderson Cancer Center continue to recommend screening mammography
because it prevents cancer-related deaths.

Benefits of mammography screening

Mammography has been used in breast cancer screening for decades and
evaluated in numerous clinical studies in various groups of patients.
An overall analysis by the U.S. Preventive Services Task Force of
multiple studies found that screening mammography reduced the risk of
breast cancer–related death by 15%–20%.

“Screening mammography is the most studied cancer screening test
available,” said Therese Bevers, M.D., a professor in the Department of
Clinical Cancer Prevention, “and it’s clear that fewer women will die
from breast cancer if more women are screened.”

Risks from mammography

A common misconception about mammography is that the radiation dose
poses a threat. Dr. Bevers said that although a person’s lifetime
radiation dose from all imaging is a concern, the radiation received
during screening mammography is equivalent to that received during a
round-trip transatlantic flight.

“It’s important to keep concerns about the radiation dose in
perspective,” Dr. Bevers said. “Screening mammography uses the lowest
radiation dose of any kind of x-ray examination.”

Another major concern is that mammography can produce false-positive
results, that is, the mammogram may show a lesion that looks like
cancer but isn’t. False-positive results can cause anxiety and lead to
unnecessary testing.

When mammography reveals a suspicious-looking lesion, the patient may
have to return to the clinic for further testing, which could include
additional mammography, ultrasonography, or even a needle biopsy to
rule out breast cancer. While these tests pose very little threat to
the patient’s health, they can be uncomfortable, inconvenient, and
expensive.

Another concern is overtreatment, which occurs when patients receive
treatment that was unnecessary. For example, it is possible for a
false-positive finding to result in treatment for a precancerous lesion
that might never develop into cancer or harm the patient if left alone.
However, Dr. Bevers said that overtreatment is much less common in
breast cancer than in some other cancers, such as prostate cancer.

The 2009 analysis by the U.S. Preventive Services Task Force found that
although screening mammography reduced the risk of breast
cancer–related death among women 40–49 years old, the rate of
false-positive findings was higher for this group of women than for
other age groups. However, Dr. Bevers said, “Forty percent of the years
of life lost to breast cancer death are from women in their 40s. While
we have to consider the possible harms, most women understand that a
reduced chance of dying from breast cancer outweighs the risk of a
follow-up test for a false-positive finding.”

Who should be screened?

Dr. Bevers said that a risk assessment is the first step in breast
cancer screening. Women can determine their risk level for breast
cancer by having a discussion with their health care providers. Among
the risk factors for breast cancer are age, family history of breast
cancer, genetic mutations such as those to the BRCA1 or BRCA2 genes,
and personal history of precancerous lesions.

MD Anderson recommends that women 20–39 years old at average risk for
breast cancer undergo clinical breast examinations without mammography
every 1–3 years. Women 40 years or older at average risk for breast
cancer should undergo annual clinical breast examinations and
mammography.

Women with a higher risk for breast cancer may begin screening
mammography at a younger age, undergo more frequent screening, or be
screened with additional tests such as magnetic resonance imaging
(MRI).

“While we may add tests such as MRI, at this time nothing replaces
screening mammography,” Dr. Bevers said. “Mammography is the only test
that has been shown to reduce a woman’s chance of dying from breast
cancer.”

— B. Tutt

For more
information, ask your physician, visit www.mdanderson.org, call askMDAnderson at 877-632-6789, or call the Cancer Prevention Center at 713-745-8040 or 800-438-6434.